Suspicious fires that have caused $277,000 in damage to seven vacant homes in west Medford in the past year have police on the hunt for a serial arsonist and residents worried for their safety.

The latest was reported at 6:23 a.m. Friday at 1947 Stewart Ave., a rental owned by OnTrack Inc.

A passer-by called 911 after seeing smoke coming from the house. Medford Fire-Rescue responded with four engines and about 20 personnel, knocking the blaze down in about eight minutes. Crews determined it started in the bathroom and identified arson as the cause.

Fire Marshal Greg Lambert estimated the damage, which was mostly confined to the interior, at about $10,000.

Housing Coordinator Shirley Wilkes said OnTrack used the income from the rental for its drug and alcohol treatment programs. She said the home's previous renters had just moved out two weeks ago and that OnTrack was getting ready to rent it out again.

"OnTrack has owned it for quite a number of years," Wilkes said. "It's not a huge financial loss."

The first in the string of fires, all considered either arson or suspicious, occurred April 24, 2012, at 1122 W. 11th St., investigators said.

"Sometimes there was clear evidence of there being an accelerant (or) some type of debris that was set on fire," Medford police Lt. Mike Budreau said. "There was no other reason for the fire to exist. In some cases there was clear evidence; in other cases, other natural causes were simply ruled out."

The other fires occurred on West Eleventh Street, Thomas Road, South Ivy Street, West Main Street, South Columbus Avenue and a second location on Stewart Avenue, police said.

"You think, 'Someone might be wandering around and decide to light something on fire,' " said Marcus Brown, who lives nearby the Stewart Avenue home that burned Friday. "It's just crazy."

He said though the targets so far have been vacant buildings, he's concerned the blazes could spread to occupied homes.

"It could happen to anybody," he said.

Chari Newman, who also lives nearby, said the possibility of an arsonist walking around is unsettling.

Investigators have not identified any suspects. There is no solid information on reports of suspicious behavior in the area during the blazes. Most of the fires were reported at night, although a couple happened during the afternoon hours.

"People are missing the part where it's actually being started," Budreau said.

Authorities said no specific property management company or individuals seem to be targeted.

"I think the only common thread here is that they are vacant homes," Budreau said.

Police advised that owners of vacant buildings should take steps to make sure the property is secured by putting locks on doors and windows. In addition, owners should keep vegetation around their properties trimmed back, which helps reduce a fire's spread and also makes it harder for would-be arsonists to come and go undetected.

Anyone with information about the ongoing case is asked to call Detective Bill Ford at 541-774-2230.

Reach reporter Ryan Pfeil at 541-776-4468 or by email at rpfeil@mailtribune.com.